This Tuesday marks the 40th observance of World Environment Day, a global day for environmental awareness organized by the United Nations in 1972.

The theme of this year's World Environment Day is "Green Economy: Does it include you?" According to the United Nations Environment Programme, a green economy, put simply, is "one which is low carbon, resource efficient and socially inclusive."

This year, the UNEP is challenging individuals to take up an activity that will make them a part of the green economy, and share their efforts with the world. Activities will be judged in one of five categories, with winners receiving a new vehicle from Kia.

The U.N. produced a green economy report in 2011 which "challenges the myth that there is a trade-off between the economy and the environment," explained a press release. The report, according to the U.N., "confirms that an investment of two percent of global GDP across 10 key sectors is what is required to kickstart a shift from the current brown, polluting and inefficient economy to a green one."

2011 was also a record year for global carbon dioxide emissions, with China leading the world in a 3.2 percent rise over the previous year's emissions levels. Fatih Birol, the International Energy Agency's chief economist, told Reuters, "When I look at this data, the trend is perfectly in line with a temperature increase of 6 degrees Celsius (by 2050), which would have devastating consequences for the planet."

Click here for a list of WED activities across the U.S. and find tips below for green activities you can enjoy with children on World Environment Day, Earth Day and every other day of the year. Scroll down for videos.

Even in the most urban parts of America, natural beauty can be found just a few miles from home. Take your child on a nature walk, or a hike on a nearby trail. Keep an eye out for exotic birds and insects (just remember not to touch!) and make sure to point out exceptionally beautiful plants.
Find the nearest nature reserve or trail near you by checking out <a href="http://www.traillink.com/" target="_hplink">Traillink.com</a>, <a href="http://www.localhikes.com/" target="_hplink">Localhikes.com</a>, or <a href="http://trails.sierraclub.org/" target="_hplink">the Sierra Club website</a>. Before you go, make sure to read <a href="http://www.rei.com/expertadvice/articles/kids+hiking.html" target="_hplink">REI's advice for hiking with kids</a>. Don't forget sunscreen, a hat, and reusable water bottles!